A car transponder I would like to see is one that coordinates self-driving cars to eliminate traffic congestion. You can do a rough version of this by reading

A car transponder I would like to see is one that coordinates self-driving cars to eliminate traffic congestion. You can do a rough version of this by reading traffic reports, but finer grained decisions would require something invasive like this. I care about my privacy, but I think privacy would lose over the safety and convenience such a system would provide.